Lathe spindle speed control mechanism



Oct. 23, 1951 Filed Sept. 8, 1948 W. G. HOELSCHER 6 Sheeis-Sheet l R INVENTOR.

ATTORNEYS.

Oct. 23, 1951 w. G. HOELSCHER 2,572,479

LATHE SPINDLE SPEED CONTROL MECHANISM Filed Sept. 8, 1948 6 SheetsShee+.

/1 2 g as 163;

Q INVENTOR.

1% /II. 190M ATTO RNGYS.

Oct. 23, 1951 w. G. HOELSCHER LATHE SPINDLE SPEED CONTROL MECHANISM Filed Sept. 8, 1948 6 Sheets-Sheet 4 ATTORNEY/S.

Oct. 23, 1951 w. G. HOELSCHER 2,572,479

v LATHE SPINDLE SPEED CONTROL MECHANISM Filed Sept. 8, 1948 v 6 Sheets-Sheet 5 JDGGING Q BUTTON 4;

FOR SPEED ANGIE IN V EN TOR.

S'IID W. G. HOELSCHER LATHE SPINDLE SPEED CONTROL MECHANISM Oct. 23, 1951 6 Sheets-Sheet 6 Filed Sept. 8, 1948 LE ER POSITIONS TTON J GING rat srzzn umuma wa BY INVENTOR. -17 Xx HM Patented Oct. 23, 1951 LATHE SPINDLE SPEED CONTROL MECHANISM William G. Hoelscher, Cincinnati, Ohio, assignor to The American Tool Works Company, Cincinnati, Ohio, a corporation of Ohio Application September s, 1948, Serial No. 48,246

8 Claims. (Cl. 116115.5)

This invention relates to machine tools and particularly to improvements in the speed change ear train and the selector mechanism of a lathe head stock for selecting quickly and conveniently the desired spindle speed.

It is customary practice to provide a wide range of lathe spindle speeds in order to rotate the Work at a cutting speed recommended for the work diameter, material, type of cutting tool, and other determinant factors. To achieve maximum efi'iciency it is important that the head stock be capable of speedy and convenient spindle speed selection in setting up the lathe for the various jobs. For this purpose the head stock transmission is provided with shiftable range selection gears in combination with speed selection gears to provide several ranges and individual speeds within the ranges. An example of this arrangement is disclosed in the patent to William G. Hoelscher, No. 2,332,381, issued October 19, 1943. This transmission may be assembled to provide either twenty-seven, eighteen or nine speeds by making a relatively simple change in the gear train. The manufacturer thus is able to standardize the head stock and may alter it to provide the required number of speeds to suit customer requirements. The present structure follows generally the principles disclosed in this prior patent and is designed to provide speedier and more convenient selectivity and improved performance.

Briefly, the present structure embodies a transmission having three speed selector levers individually connected to the range and speed change gears and arranged to be operated individually but in combination with one another in such manner that primary and secondary range changes and individual speeds are selected individually by shifting the levers relative to the positions indicated by a speed indicating plate mounted in operating relationship with the levers.

A primary object of the invention has been to improve the speed efficiency and general performance of the transmission by the use of individually shiftable control levers which are operable to select the desired range and speed directly instead of progressing through a series of speed changes to reach the desired gear combination.

In its preferred embodiment, the speed selection unit includes an indicating plate having several vertical columns of figures indicating individual spindle speeds. A horizontally movable lever swings relative to the vertical columns to establish a speed or range selection which includes all the speedsin a given column. Asecondary speed or range selector lever swings verticall and has a series of positions for secondary range selections. Another speed selection is made by a vertically movable lever similar to the secondary range lever, which moves in registry with several horizontal groups of speed indicating figures on the indicating plate. The final spindle speed therefore is determined by the position of this lever combined with the positions of the primary and secondar range selector levers. In making a speed selection, it is not necessary to pass sequentially through a series of speeds to reach the one desired or to operate the levers in any particular sequence, and in many cases, the operator need shift but one or two levers to make the desired selection. This increases the efiiciency and speed of selection and avoids the dilficulty of passing through one or more sets of change gears and the physical difficulty of meshing and unmeshing a series of gears.

A further object of the invention has been to provide a simplified and easily operated system of selector levers in combination with a speed index plate to provide individual lever operation correlated to the index plate for direct reading of spindle speeds for various lever combinations.

Still another object has been to provide a sim: plified direct acting mechanism connecting the several selector levers with the shiftable gears to provide smooth and easy shifting, to reduce the number of parts, and to permit the manufacturer to convert the head stock for various speed combinations with a minimum of alteration.

Further objects and features of the invention will be more fully disclosed with reference to the specification in connection with the drawings.

'In the drawings:

Figure 1 is a general perspective view illustrating a lathe incorporating the improved hea stock. Figure 2 is a developed sectional view of the head stock gear train, the various transmission shafts and component gears being located in a common plane for convenience of illustration.

Figure 3 is a top plan view of the head stock with the cover plate removed to illustrate the general structure and arrangement of the transmission.

Figures 4 to 7 inclusive are developed views 0 the various gear shifting cams.

Figure 8 is a sectional view taken on line 8-8,

Figure 3, illustrating the mounting and actuating mechanism for the cams. Figure 9 is a sectional view taken on line 9-9,

Figure 3, illustrating the selector levers, cam driving gears and shifter levers in conjunction with the transmission.

Figure is a sectional view taken on line 10-40, Figure 3, detailing another portion of the gear shifting apparatus.

Figurell is a face .view of one of the speed indicating panels. a

Figure 12'is a fragmentary sectional view illustrating a portion of the transmission with a two speed interchangeable compound gear installed in place of the three speed gear shownin Figure 2, to provide eighteen speed changes instead of twenty-seven.

Figure 13 is a developed view of the cam which is installed in conjunction with the :two speed interchangeable gear shown in Figure 12, in place of the cam illustrated in Figure 5.

Figure 14 is a face view of the speed indicating panel which is used in conjunction with the eighteen speed transmission.

" Figure 'l-5'isa fragmentarytopplan view similar to Figure 3, illustrating the cam and lever arrangement for the nine :speed transmission.

Figure 16' is *a fragmentary sectional view similar to Figure '12, with the interchangeable shiftable gear omitted 'anda fixed gear installed on the inputshaft to provide nine speedsinstead of eighteen as previously described.

Figure '1-7-is-a face view of the speed indicating panel which "is used in conjunction with the transmission whenit'is arranged "for "nine speeds.

Referring to Figure 1, the improved head stock indicated generally at 20 is incorporated in a lathe having the usual bed 2|, tail stock '22 and g A feed box 2 1 is mounted "to one carriage 23. sideoi the head stock in'driving connection-with the 'head stock gear train to control "the speed of the lead screw '25 and feed'rod 26. The carriage includes 'a gear train which is driven by feed rod 26 and which meshes with-therack '2"! to translate the carriage longitudinally relative to the bed. Thecarriage further includes 'a nut which is engageable with *the lead screwfor feeding the carriage by power-from the "lead screw. The head stock includes a spindle indicated generally at 28 "Which may include "the usual face plate 30. 'The -head stock providesa series of spindle speeds which are selected by means -'of the speed change unit generally 'indi- Speed-seZector-system As shown in Figures .1, '3 and 10, the various spindle speeds are selected 'by means of three levers which are pivotally mounted relative to the speed control unit .3l. Of .these, lever .32 may be designated a primary'range selector "and 33., a secondary range selector. .Lever v34 .is a speed selector lever and operates in conjunction with lever '32 and 33 to determine the .final spindle speed selection dependent upon the position of "levers .32 and '33.. 'Theselevers are positioned in accordance with .a speed indicating plate 35 which is mounted at the face of speed control "unit 3 I to indicate the various positions of the three levers for the various speeds. AS shown in "Figure 11, illustrating the indicator plate fora twenty-seven speed transmission, .the plate 35 isprovided with three vertical columns 3B'of speed indicating figures. Lever .32, which swings in a horizontal path, has three positions 4 corresponding to the vertical columns 36 and is positioned in alignment with these columns to select the range.

In making a speed selection, the primary range selector lever 32 first is shifted to a position in alignment with the vertical column of range speeds which includes therequiredspindle speed. For example, .if the transmission is to be set for 86 R. P. M., lever 32 is swung into alignment with the central column. The plate includes also three horizontal groups of figures corresponding Etc. the .positionspf lever 34. There are three rows ao'fafigures in each group and these rows each are individualized by three stripes of distinguishing colors indicated at '31, 38 and 43. The distinguishingcolors are-duplicated in each horizontal group. As shown in Figure 10, the secondary range selector lever 33 swings in a vertical path relative to a color index plate 4| bearing three colors, indicated at 311138 a and 42a, corresponding to the colors of the indicating plate. Lever 33 is swung 'to .a position in registry with the color block 31a corresponding .to the color stripes 31, "the lower one of which includes the 86 R. P. indication. The final spindle .speed selector lever '34 next'is swung downwardly into alignment with the lower horizontal group of figures which includes 1'86 R..'PI. IM. 'By means of these three levers the various s'hiftable gears are meshed in the proper combination to .deliver .by desired spindle speed as hereinafter disclosed in detail. It will be apparent that the levers may be shifted in any desired sequence convenient to the operator.

When the transmission assembled to provide eighteen speeds instead of twenty-seven, the lever arrangment is substantially the same .as above outlined. However, in place o'f'the three color arrangement, the speed index plate .42 .is provided with two color ranges as shown in Figure 14. In this instance, the color selector lever 33 becomes a two position *lever, operating 'in conjunction'with the colors of the .plate '42. 'Thus. there is provided three primary range positions for *lever 32, two secondary range selection positions for lever 3,3, and 'thre'ejfirra'l speed selecting. positions for =lever 24;"170t2t11i11g eighteen spindle speeds. *When the transmission is assembled ;to. provide nine speeds the color selector lever 33 .is omitted 'as shown in .Figuref15. The speed index plate in this instance "is'provided with nine positions as shown in Figure 17; three'for the primary range selector "lever 32 and three for the final speed selector lever 34, thus providing a. totalof nine spindle-speeds.

To facilitate 'meslringithe various gears, a jogging button indicated'at w (Figure 11) is provided at the front of the speed control unit. 'This button is in electrical connection with the main motorthrough an electrical component. connected to themotor .to jog or momentarily energize the motor. When the operator encounters difficulty in meshing the .gears during selection, he depresses the jjogging button. .to cause the motor. to partially rotate the gears of the transmission to reposition the .gear .teeth .for engagement with the mating gear teeth. .By reason of the individualflevers, the gear selections .ior the various combinations are made directly so that it is notv necessary to .passseguentially through a. number .of gear changes toreach the desired-speed selection. This, in-lcombination with the jogging apparatus,,provides .maximum speed .and conveniencein .arriv'ingrat -the:gear ratio'for the desired:

spindlespeed. V v V Speed change transmission Described with reference to Figure 2, illustrating the transmission assembled to provide twentyseven speeds, the transmission casing 45 includes end walls 4646 and intermediate webs 41 to provide bearing supports for the various transmission shafts and spindle. The transmission unit is bolted to the inner ways of the lathe bed as shown in Figure 10. Power is transmitted from the main motor (not shown) to the head stock by means of multiple V-belt pulley 48 keyed to the input shaft 58 which is journalled in roller bearings 5I- -5l mounted in the casing 45. A shiftable primary compound gear 52 including gears 53, 54 and 55 is slidably splined to the input shaft 58. An intermediate shaft 56, journalled on roller bearings 51, is mounted parallel to shaft 58. A series of gears, mating with shiftable gear 52, is keyed to shaft 56. The shiftable compound gear 52 is slidable to three positions by means of the secondary range selector lever 33 as hereinafter described. It is to be noted that the shiftable gears all are shown in a neutral position in Figure 2. When compound gear 52 is shifted to the extreme left as viewed in Figure 2, gear 55 meshes with gear 58 in the intermediate position, gear 54 meshes with gear 68 and in its right hand position gear 53 meshes with gear 6|. The shiftable compound gear therefore drives intermediate shaft 56 at three different speed rates.

A second intermediate shaft 62, journalled in roller bearings 63-63, is rotatably journalled parallel with shaft 56. A three position compound gear unit 64 is slidably splined to shaft 62 and is provided with three speed change gears 65, 66 and 61. Speed change gear unit 64 is shifted by means of the spindle speed selector lever 34 as hereinafter described. When the unit 64 is shifted to the left as viewed in Figure 2, gear 6 1 meshes with gear 58. In its intermediate position, gear 66 meshes with gear 68, and in its extreme right hand position gear 65 meshes with gear I8. The shiftable compound gear unit 64, in combination with the shiftable unit 52, provides nine speed changes from shaft 58 to shaft 62.

Shaft 62 further is provided with a clutch and gear unit H which is slidably splined thereon and which is shiftable by means of the primary range selector lever 32, either into mesh with gear I2 or directly into clutching engagement with the internal clutch teeth I3 formed on gear I4 which is loosely journalled upon ball bearings I5 mounted on shaft 62. The clutch and gear unit 'II includes gear teeth I6 and when shifted to the left these provide a, meshing engagement with the teeth of gear I2. When the unit II is shifted to the left into mesh with gear I2, gear "I2 drives shaft 11 which is loosely journalled on roller bearings 18-16 and which includes an elongated gear 88.

A shiftable compound back gear unit I9 includes a gear 8| in constant mesh with gear 88. Gear unit I9 is keyed as at 82 to an idler shaft 83 and includes a pinion 86. When the unit I9 is shifted to the left, gear 8I meshes with a pinion 81 keyed to the lathe spindle 88, and when it is shifted to the right, pinion 86 meshes With a gear 98, likewise keyed to the spindle 88. Spindle 88 is journalled in ball and roller bearings as hereinafter disclosed. When the gear and clutch unit 'II is shifted to the right to engage the clutch teeth of gear I4, the gear and pinion unit 88 automatically is shifted to a neutral position as shown in Figure 2 and the drive is from gear 14 to a gear 89 which is keyed to the spindle 88.

From spindle 88 there is provided a power takeofl to drive the feed box 24. For this purpose a pair of gears 9I and 92 is keyed to the rearward end of the spindle. An idler gear 93 is in constant mesh with gear 9I' and a slidable reversing gear 94 is adapted selectively to mesh either with gear 92 or idler gear 93. Reversing gear 94 is slidably splined upon an output shaft 95, the outer end of which is provided with an output gear 96 meshing with an idler gear 91. Idler gear 91 forms a part of the gear train leading to the feed box transmission.

As shown in Figure 8 a shifter rod 98 includes a yoke I88 engaging the reversing gear 94. A detent I8I (Figure 10) engages the inner end of shaft 98 to latch the reversing gear either in neutral, forward or reverse positions. When the gear 94 is meshed with gear 92, the feed box is driven in the forward direction. When it is meshed with idler gear 93 the power is transmitted from gear 9| to idler 93 to reversing gear 94 which is in mesh with the idler in this position, thereby driving the shaft in the reverse direction.

As shown in Figure 2, the transmission is provided with a lubricant pump I82 which distributes lubricant to the various gears and bearings of the transmission. This pump is driven by a gear I83 keyed to the power input shaft 58 and meshing with driven gear I84 keyed to the pump shaft I85. This provides constant operation of the lubricant pump at a uniform speed whenever the head stock is running.

The spindle 88 is journalled at its forward end upon a pair of tapered roller bearings I86 and I81. Since it is important to provide anti-friction bearings and to eliminate looseness, adjust:

ment means are provided for conveniently adjusting the bearings I86 and I81 to take up for Wear and looseness. race of bearing I8! is engaged by a nut I88 screwthreaded into the web 41 as at H8. The outer end of the nut includes a flange I I I having gear teeth meshing with a worm I I2 which is secured upon a shaft I I3. As shown in Figure 9, shaft H3 is journalled in lugs II4-I I4 forming a part of the intermediate web 4'! and the outer end of theshaft is journalled in the front Wall of the casing 45. Shaft II3 includes a squared end II5 covered by a removable closure cap II6. When bearing adjustment is necessary, cap H6 is removed and a suitable instrumentality is slipped upon the squared end of the shaft. Rotation of the shaft is transmitted through worm II2 causing rotation of the nut I88 which in turn forces the outer race of bearing I8I rearwardly to compensate for wear. The rearward end of spindle 88 is journalled in a ball bearing 8 which resists radial loads only.

Summary of gear train operation and gear unit II is shifted to mesh with gear I2, the power is transmitted from shaft 62 to shaft I1 and from shaft 17 to idler shaft 83 to drive the spindle either from gear 8I to pinion 8I or from pinion 86 to gear 98. in order to.

For this purpose the outer prevent niterierenc'e; the baek gear unit 1 9 -and clutch and gear unit II are interconnected and are operated :in common from the range selector lever '32. The: arrangement issu'ch that the back gear unit :19 is in neutral when the clutch and gear unit I I is in direct clutching engagement :gear 7 1. When: the clutch and gear unit is in mesh with the gear 32, the back gear unit 19 :is free to be shifted in either direction establisha :meshin'g engagement either with 811 :or :g'ear When the transmission is assembled to deliver eighteen :speeds instead of twenty-seven, a two speed shiftable component gear 52a-is=instal1ed on the shaft i513 as shown in :Figure 12, instead of the three speed gear illustrated in Figure 2. Also, a "modified. two position shifting cam (Figare 13 .is installed instead of the three positioncam used for gear 52. In --order' to provide the nine'speed. transmission the 'shifitable gear 52 :is omitted-entirelvand instead a single fixedgear 52b ziscinstalle'd on shaft 56 as shown .Eigure 116. Gear 521) (Figure 16;) is fixed' 1110' shaft 50 byumeans of a set "screw I20 andzis'in constant mesh with the :gear 6Z0, The cam u'tilizedxfor shifting gears 52 and 52a is omitted entirely this instance. shown inr'Fi'gure 15, theulever 33 which actuates the shiftable compound gears 52 and-52a, together with its:a;ctuating cam :also is :omitted from the nine speed assembly.

Gear shifting mechanism i ls noted with reference to the gear train, the twenty-seven speed transmission includes shiftable gear units 52, 64, II and 19-. Each of these several gears, as shown 'in "Figure 3, are selectively shifted by means of an individual shifter lever having-one end engaged with the shiftable gear and the opposite endconnected to the track of a cam which shifts the various levers "to the required positions for meshing the gears. 'The cams for-gear units 52 and 64 are actuated independently of each other by selector levers 33 and 34, while the cams for the units H and- T9 are actuated :in-common Joy lever "32 to provide automatic interaction of the two units. shown, the three position sliiftalile compound gear 64 is controlled by the shifter lever I22 which is pivoted as at I23 to the casing. The

inner end of lever 1 22 includes a shifter yoke I24 {Figure '10-) engaged in the groove I 25 of compound gear '64. The oposite end of'l'ever I22 is engaged in 'a-"cam "track 126 formed in the periphery of cam I27 (Figure 3). The track IZfi', "as "developed in Figure 4, provides three pos'itions for gear unit "64 as the camis'rotated.

Cam I2! is connected to the spindle speed selector lever '34 as illustrated in Figures 3, 8 and 9. .As shown, selector lever 34 "is provided with a shaft I28 "to which fixed a gear sector I36. Gear sector I36'meshes with a gear I31 secured to shaft .I-32.. .The opposite end of shaft I32 carries a gear I33 which meshes with the gear teeth 13! formedon the-end of cam T21. Lever 35 has three positions similar to lever 33 -'as shown in Figure 9 and when it is actuated it rotates the cam 121 to its three positions. As shown in "Figure '3. gear 61 of unit 64 is in its intermediate speed position, meshing with gear 58. Rotation of the cam causes lever I22 to shi'ft'compound gear 64=to-the rightto mes'hwith its component *gears 66hr 10.

i'ls shown in Figures 4 and 10, cam I21 includes aseries of de'tent notches I35 engaged by a roller -I36-carried by lever"I"3"I. 'Lever 131' is pivotallwmounted as "at #38 its opposite endiis engaged :by a tension spring I40 to urge roller :I36 into engagement with notches 11:35. This arrangement :latches the cam .to :maintain the gear sin its selected position.

.Theshiiitable compound :gear unit 52 onshaft 5.6, which .-is-controlled by the secondary range selectorlever 33, is shifted by :a shifter lever .141, actuated by -a 'cam I43 having a track 1411 to provide three .positions. As shown in Figure 3;, gear 52 .isiin its intermediatespeed rposition with its .gear 53 meshing with gear 6|. It is shifted byemeanspfa yoke I45 engaging the groove =I46 of gear 52 Yoke t45 includesraslider I41 :mounted upon af-pai-r of slide rods I48. The swinging end -.of lever I4I -.connects with slider I48 by means 0f a ,pivot pm 4 50.

6am M43 is actuated by selectors .lever -33 in the :following manner. As :shown in Figures 3, 8 and- 9; selector lever 33 is connected to a gear sector I5I in the same manner as is lever 34. Sector =I5I .meshes with agear I52 (Figure 8) secured zto a sleeve I 53 telescopically mounted upon and rotatable relative to shaft I32. A gear 1:54:18 secured to the inner end of sleeve t5r3-and meshes with the .gear teeth I55 formed on-the end 'of cam #43. :Movement of lever :33 in either 'direction from the intermediate -position shown' causes rotation of @cam I43 :to shift;

compound gear :52 "130' the left to mesh with .gear 56- 'or $13. Cam I43 .-is provided with a :detent arrangement -56 (Figure 3) which follows the eonstruction disclosed with reference to cam I2'I.

The range selector lever 32 shifts both the clutch and -gearunit II and the-compound gear unit &9. )For this purpose a :pair cf cams I58 and: :iBOware driven in unison by means of lever 32. [As shown in Figures 3 and 9, spiral gear sector +6I is secured to the shaft I 62 of lever 32. Sector iI-6-I :meshes with a spiral gear I63- secured-tothe camshaft I 64 upon which is fixed the roams 4 58 ;and I613. The clutch and gear unit H connected by a yoke I65 pivotally mounted as 'at 166 to the swinging :end of a shifter lever I61. The opposite end of lever :I-6"'I is engaged inthe :track I68 of cam I53. The compound z-gear unit 19 isengaged by Ia yoke L69 carried by :a slider I10 mounted upon the slide vrods 148' and engaging the opposite sides of ;gear -8 I. Slider H0 is pivotally connected as at -I-'iI to a shifter lever I13 :having its opposite end engaged. in the cam track =I-.'I-4 -iof viously described, engages a series of notches in-cam 166 to latch the cams I58 :and theirselected .pos'itions.

'When the range selector lever '32 is shifted to the left. from the intermediate position shown in. Figure 3, cam-s 4 58 and I63 are rotated in unison causing lever I61, for clutch gear unit "I I, to .remain stationary with its gear :16 in mesh with the gear 'T2,.since this portion of cam track [61 is straight. .Cam track 114 of cam I66 how-- ever, will cause the s'hiftable component 13 to be shifted toward the right to mesh its pinion 86 with the large spindle .gear 90. The drive then wiIlYbe transmitted from shaft I-I, gear 8| pinion .86,- gear to drive the spindle at its low speed range. When the lever 32 .is shifted to the right, roam track 168 of cam 1.58 will cause its -lever 'ITBT to shift the clutch and gear unit lit 'to the right to mesh gear I6 with clutchteeth '14,. thus driving the spindle directly .from shaft 6'2, .gear 'T4 to spindle gear 89'. the lever to the right also causes track I14 of I 6.0 :in.

Shifting cam I60 to shift the component 19 to a neutral position.

From the foregoing it will be observed that when the range selector lever 32 is operated, the

cams I58 and I60 automatically shift the clutch and gear unit H and compound gear 19 in predetermined sequency to provide the three ranges. Thus, when the lever is shifted to its left-hand position to select the low speed range, clutch and gear unit H remains in its left-hand position in mesh with gear 12 and shiftable compound gear unit 19 is shifted to the'right to mesh pinion 86 with spindle gear 99. Thus, the low speed ratio is established from shaft 62, gear 16 to gear 12, driving shaft 17 at reduced speed and from shaft 11 throughthe elongated gear 80 to gear BI and from pinion 86 to spindle gear 90. This provides maximum gear .reduction from shaft 62 to the spindle shaft. The several secondary range and spindle speeds for the low speed range are established by the shiftable compound gears 52 and 64 to establish a series of speed changes between the input shaft 50 and shaft 82.

When the range selector lever is in its intermediate position, the gear and clutch unit H remains in mesh with gear 12 to drive elongated gear 8!] as above described. In this instance however, the component gear 19 is shifted to the left to mesh large gear 8| with the spindle pinion 81 to provide the intermediate range. When the lever is shifted to its righthand limit for the high speed range, cam I58 shifts the clutch and gear unit to the right to couple shaft 62 directly to gear 14 which meshes with spindle gear 89 to drive the spindle directly from shaft 62 instead of through the back gear unit 19. In order to permit this operation, the compound back gear unit 19 is shifted to a neutral position.

By virtue of the range selector lever'32, in combination with the color selector lever 33, various gear changes are achieved with maximum convenience and dispatch since each se lection is made directly without passing the varrange selector lever 33 is moved with reference to its color index plate to coincide with the color for the required spindle speed. This shifts the three speed compound gear 52 to one of its three positions to provide a secondary range. The spindle speed is selected when the speed selector lever 34 is move-d to a position with reference to the index plate 36 in alignment with the desired group of three colors. This shifts the three speed shiftable gear unit 64 into mesh with one of its mating component gears 58, 68 or IE3 to provide the selected speed.

When the transmission is assembled for eighteen speeds instead of twenty-seven, the two speed selector gear 52a is installed. In thisinstance, the secondary range selector lever 33 is provided with two positions instead of three. In this case the color index plate 4| is provided with two colors instead of three and the index plate 35 correspondingly is in two colors instead of three as shown in Figure 14.

It will be observed that the shifting apparatus is of maximum simplicity and compactness and the manufacturer is able conveniently to furnish the lathe equipped for the desired speed simply by installing the proper speed change gear 52,

52a or 5212 and by installing the necessary cam to provide two or three shifts or by omitting the cam entirely when the fixed gear 521) is installed.

Having described my invention, I claim:

1. In a head stock for a lathe or the like, a spindle, a gear train, a plurality of 'shiftable speed change gear units in said gear train to vary the spindle speed, a shifter arm operatively connected to each of said speed change gear units, two of said units being interrelated and adapted to be shifted relative to each other to provide a series of speed ranges, a cam shaft, a pair of cams fixed to said shaft and connected to the shifter arms of said interrelated speed change units, a selector lever in operative connection with said cam shaft to actuate said pair of cams in unison, a second group of cams loosely journalled on said shaft, individual selector levers operatively connected to .said loosely journalled cams operable to shift the same independently of said fixed pair, and a respective shifter arm connected to said cams.

2. In a speed change transmission for a head stock or the like, a plurality of shiftable speed change gears, a cam connected respectively to each of said speed change gears for shifting the same, a cam shaft for mounting said cams, one group of said cams being fixed relative to said cam shaft and the other of said groups being loosely journalled thereon, a selector lever in driving connection with said cam shaft for actuating said first group of cams in unison, an operating shaft journalled adjacent said cam shaft and in driving connection with one of the cams loosely journalled on said cam shaft, a second selector lever operatlvely connected to said operating shaft and adapted to actuate said loosely journalled cam, a third selector lever for the other of said loosely journalled cams, and con necting means associated with said other of the loosely journalled cams and said third selector lever to actuate said cam independently of the other of said cams.

3. In a speed change transmission for a head stock or the like, a plurality of shiftable speed change gears, cams connected respectively to each of said speed change gears for shifting the same, a cam shaft for mounting said cams, said cams being arranged in groups relative to said cam shaft, one group of said cams being nonrotatably fixed to said cam shaft and the other of said groups being loosely journalled thereon, a selector lever in driving connection with said cam shaft for actuating said first group of cams, an operating shaft journalled adjacent said cam shaft and in driving connection with one of the cams loosely journalled on said cam shaft, a sleeve loosely journalled on said operating shaft and in driving connection with the other of said loosely journalled cams, and a pair of selector levers connected respectively one to the sleeve and one to. the operating shaft and adapted to actuate the loosely journalled cams independently relative to each other and to the cam shaft.

4. In a speed change transmission for a head stock or the like, a plurality of shiftable speed change gears, cams connected respectively to each of said speed change gears for shifting the same, a cam shaft for mounting said cams, said cams being arranged in groups relative to said cam shaft, one group of said cams being nonrotatably fixed to said cam shaft and the other of said groups being loosely journalled thereon, a selector lever in driving connection with said cam shaft for actuating said first group of cams, an operating shaft journalled adjacent said cam shaft and 

